Optimization and validation of simultaneous analyses of ecgonine, cocaine, and seven metabolites in human urine by gas chromatography–mass spectrometry using a one‐step solid‐phase extraction

Abstract

The presence of ecgonine in urine has been proposed as an appropriate marker of cocaine use. Only a few methods have been published for their determination along with cocaine and the rest of its metabolites. Due to their high polarity and consequent solubility in water, these have low recoveries, which is why it is necessary to increase the sensitivity, by the formation of hydrochloric salts or multiderivatization of the analytes or by performing two solid‐phase extractions (SPEs), considerably increasing the time and cost of the analysis. This work describes a fast and fully validated procedure for the simultaneous detection and quantification of ecgonine, ecgonine‐methyl‐ester, benzoylecgonine, nor‐benzoylecgonine, m‐hydroxybenzoylecgonine, cocaethylene, cocaine, norcocaine, and norcocaethylene in human urine (500 μL) using one SPE and simple derivatization. Separation and quantification were achieved by gas chromatography–electron ionization–mass spectrometry (GC–EI–MS) in selected‐ion monitoring mode. Quantification was performed by the addition of deuterated analogs as internal standards. Calibration curves were linear in the adopted ranges, with determination coefficients higher than 0.99. The lower limits of quantification ranged from 2.5 to 10 ng/mL. The intra‐ and inter‐day precision, calculated in terms of relative standard deviation, were 1.2%–14.9% and 1.8%–17.9%, respectively. The accuracy, in terms of relative error, was within a ± 16.4% interval. Extraction efficiency ranged from 84% to 103%. Compared with existing methods, the procedure described herein is fast, since only one SPE is required, and cost‐effective. In addition, this method provides a high recovery for ecgonine, resulting in a better alternative to the previously published methods.

Determination of N,N-dimethyltryptamine and beta-carbolines in plants used to prepare ayahuasca beverages by means of solid-phase extraction and gas-chromatography–mass spectrometry

“…In order to optimize the extraction procedure, a total of four different techniques were tested. These techniques were chosen based on the available literature for similar compounds, since specific data for the target analytes is scarce [14]. The elution step was the studied parameter, using different solvents and different concentration levels.…”

Quantification of Cannabinoids in Cannabis Oil Using GC/MS: Method Development, Validation, and Application to Commercially Available Preparations in Argentina

“…An initial prescreening (methanol and 5 min sonication time) of cannabinoids was made in full scan mode. Mass spectrometric identification criteria were according to the WADA [34,35]. The cannabinoids identified were Δ 9 -THC, CBD, CBN, CBC, CBG, THCA, and CBDA.…”

“…The linearity of the method was established on aliquots of ethanol (100 μL) spiked with the corresponding working solution to obtain calibrator samples. Replicates (n = 9) at each concentration were analyzed as described Fernandez et al [35].…”

Cocaine: An Updated Overview on Chemistry, Detection, Biokinetics, and Pharmacotoxicological Aspects including Abuse Pattern

“…This method was successfully applied to 1 mL samples of urine, saliva and plasma, 50 mg of hair, and sweat extracted from a sweat patch, yielding limits of detection for AEME of 1 ng/mL for the first three matrices (with a linearity range of 5-1500 ng/mL), 0.1 ng/mg for the hair (with a linearity range of 0.2-25 ng/mg) and 0.5 ng/patch (with a linearity range of 2-100 ng/patch). Recently, published research by Fernandez et al described a validated method for the detection of cocaine and several of its metabolites in 0.5 mL of urine samples, resorting to a simple derivatization step following a solid phase extraction (SPE)-the method achieved low limits of quantification from 2.5 to 10 ng/mL by using GC-MS with electron ionization [40]. Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was also successfully employed to detect cocaine and BE both in urine and oral fluid [41], as it was ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) in dried blood samples [42].…”